Income taxes - Carryforward (Details) € in Thousands	Dec. 31, 2016 EUR (€)
Corporation tax
Carryforward
Gross loss carryforwards	€ 20,481
Trade tax losses
Carryforward
Gross loss carryforwards	20,100
Foreign loss carryforwards
Carryforward
Gross loss carryforwards	€ 12,499

The amount of unused tax losses for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax losses [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2016-01-13
-Paragraph 81
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2016-03-30&anchor=para_81_e&doctype=Standard
-URIDate 2016-03-31

Name:	ifrs-full_UnusedTaxLossesForWhichNoDeferredTaxAssetRecognised
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant